This application claims the priority of German Application No. 10 2004 062 794.0 filed Dec. 20, 2004, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a rotor cup for an open-end spinning device, which comprises a supporting base body, which is provided with an insert comprising a fiber guiding surface and a fiber collecting groove, which insert is radially centered in the base body and axially supported thereon with a stopping face.
In the case of a rotor cup of this type (German published patent 15 60 307, corresponding U.S. Pat. No. 3,439,487) the two-part rotor cup comprises a base body having a high strength and an insert which comprises the fiber guiding surfaces. This insert is inserted into the inside of the base body in the form of a pot-shaped lining, said insert comprising the fiber sliding surface as well as the fiber collecting groove, both of which are designed to achieve the best spinning properties. Due to the present standard high rotational speeds of the rotor cup, the base body is subject to very high centrifugal forces, which results in the walls of the base body which hold the insert expanding. There is a risk that the insert becomes loose thus rendering the rotor cup unusable.
In the case of a similar two-part rotor cup of this type (German published patent application 2551 045) a base body is provided which is suitable for high rotational speeds, said base body being provided with a wear-resistant, pot-shaped insert made from sintered ceramic which comprises the fiber guiding surfaces. Here the insert can be bonded or pressed into the base body. Apart from the aim of achieving good wear protection, nothing further is disclosed about this rotor cup.
It is an object of the present invention to design a rotor cup of the above mentioned type in such a way that the centrifugal forces occuring at high speeds are not damaging. It should be hereby possible to produce one and the same base body and to equip it with various inserts according to the desired application.
This object has been achieved in accordance with preferred embodiments of the present invention in that the insert is crimped into the base body.
Because the edge of the base body is crimped over the insert according to certain preferred embodiments of the invention, the insert is affixed in radial and in axial direction, which ensures that the insert cannot become loose even at high speeds. The same base body having constant dimensions can be used for the entire production, into which base body a variety of inserts having different functions can be inserted. This can involve varying diameters, various forms of the fiber collecting groove or different materials of the fiber guiding surfaces. The base body can be made of steel or aluminum, while the insert can be made of steel, ceramic or sintered material as desired according to certain preferred embodiments of the present invention. In addition, the fiber guiding surfaces of the insert can be coated according to the desired spinning conditions or the service life without the base body having to be treated in the same way according to certain preferred embodiments of the present invention.
Preferably the insert is supported in the base body in the area of the fiber collecting groove only according to certain preferred embodiments of the present invention. This results in a significant saving in material in relation to the base body in comparison to the above mentioned prior art.
In certain preferred embodiments of present invention, the insert is provided on its outer side facing away from the stopping face with a ring groove for the purposes of crimping.
During crimping, the stopping face is pressed tightly on the base body and radially secured due to the ring groove. The insert itself is designed essentially as a conical ring, corresponding to the slope of the fiber sliding surface, whereby the inside of the rotor cup has its biggest diameter at the fiber collecting groove according to certain preferred embodiments of the present invention.
The present invention also relates to a process for producing a rotor cup of the above mentioned type. A semi-finished part made of plastically formable material and having a pot-shaped take-up part having an open front face is produced for the formation of a base body, in which semi-finished part a finished insert is placed, which subsequently is secured by means of crimping over a front edge of the take-up part, which subsequently forms the base body, according to certain preferred embodiments of the present invention.